I've had a Paul C. Buff White Lightning X2400 studio strobe that I've used lightly for a few years and would like to start using it more outdoors where a lot of flash power is needed. In my initial tests, which I expected to show the X2400 was vastly more powerful than my Nikon SB-900 flash, I didn't see the huge increase in brightness I was expecting.

Comparing histograms, the 1/8 power X2400 shot plus 1/3 stop looks about the same as the full power Nikon SB-900 shot. So the X2400 is not quite 3 stops more powerful than the SB-900. Does that sound about right? I suppose 3 stops is a lot, but I was expecting a bigger win for the X2400.

Your results are what I would expect. If you really want to compare, put the strobes on a stand and go bare bulb. Get a lightmeter to make your measurements.....typically 10' away. If you put the diffusion cap on the Speedlight that will be very close to a bare bulb studio strobe. They become comparable then.

GN=f*Distance.

If we only talk about energy, then let's compare the Speedlight:

The SB800 has a 1400μF capacitor and the normal charging voltage is 330V. The stored energy is 0.5CV^2=76.2J or 76WS. I have a repair manual, but I can not see the value of the cap. Since the SB-900/SB-910 are about the same GN and the voltage is the same, I assume the capacitor is the same....1400μF.

So at 76WS max energy delivered to the flashtube, it is fairly weak flash system by itself, but since it is going into a housing that concentrates the flashtube's power, it becomes more effective. Light modifiers, room dimensions all have an effect on flash readings. Rest assured, your X2400 strobe is far more powerful than your Speedlight....by about 13 times as much under the same conditions. 1000WS/76WS.

It is all about how much energy is delivered to the tube and how you modify the light output. I own 3 Speedlights, several monolights, and I just received an Einstein (E640) with a Power MC2 and the Vagabond Mini. I took light readings today comparing SB-900/SB-910 (76WS), Flashpoint 2420 Monolight (1200WS), Flashpoint 1200 Monolight (600WS) and the Einstein E640 Monolight (640WS). I will post the numbers here after I put them in a better format.

I use a tri-socket for up to three Speedlights into an umbrella, though at that point, with pocketwizards and external packs for the speed lights, it becomes more of a pain than benefit. Would rather use my Einstein setup at that point and have three times more workable power to control.